1. Field of the Invention
This invention relates to an inflatable genitourinary prosthesis and to a disposable cartridge assembly for hypodermically positioning, injecting and inflating the prosthesis so that increased occlusive pressure may be controllably applied to a patient's urethra for holding the patient continent. The prosthesis includes an expandable antimigration membrane which may be percutaneously infused with fluid or suspended particulate matter so as to simultaneously increase localized tissue volume while preventing the possible migration of such fluid or suspended particulate matter.
2. PRIOR ART
As will be known to those skilled in the art, in cases where the natural sphincter muscles of a patient have been surgically excised, damaged by disease or compromised by physical trauma, an artificial prosthetic sphincter has often been implanted so that occlusive pressure may be applied to the urethra to restore continence. Artificial sphincters are well-known and specific examples thereof will not be listed. However, the implantation of an artificial sphincter commonly requires a surgical procedure which necessitates the hospitalization of the patient. Such a procedure is relatively complex and expensive, and usually requires six to eight weeks or more of recovery time. Accordingly, both the patient and his physician face approximately two months of delay before being able to actuate the prosthesis to ascertain whether the surgery has been successful and the patient is continent. More particularly, because of the swollen and aggravated condition of edema of the urethral tissues during and for a period subsequent to surgery, the physician cannot precisely match the occlusisve pressure available from the prosthetic sphincter to the patient's urethra. Therefore, the physician must estimate the required minimal occlusive pressure needed to achieve urethral coaptation in that particular patient. As a consequence of such estimate, sphincteric mechanisms are often improperly selected or fitted, so that the occlusive pressures generated by such mechanisms are either insufficient to successfully achieve continence or excessive to the point of causing ischemia and subsequent erosion of urethral tissue. Excessive occlusive forces may undesirably minimize arteriovascular blood flow to the urethra and thereby cause ischemia and subsequent erosion of the delicate tissues. What is more, if the implant surgery should prove to be unsuccessful (i.e. the maximum occlusive pressure to be generated by the sphincter is insufficient to hold the patient continent or the sphincter malfunctions mechanically), then additional surgery becomes necessary to provide sphincter adjustment, repair or explant.
In the recent past, it has been suggested that urinary incontinence may be successfully treated by non-surgical means with the periurethral injection of TEFLON paste (e.g. "POLYTEF") to increase localized tissue volume and thereby increase the available occlusive pressure to be applied to the urethral mucosa of an incontinent patient. However, this suggested treatment may lead to potential problems as a consequence of the migration of the paste from the injection site. That is, such paste has been known to induce tissue reaction and form TEFLON-induced granulomas in certain individuals. Because of the possible tissue reaction to TEFLON-based paste, concern for patient safety has also been expressed. Hence an otherwise advantageous, non-surgical procedure has now fallen into some disfavor.